81 x 9 = 801. What must you do to make the this equation true?

You have two buckets of 11 liters and 6 litres.
How can you measure exactly 8 litres?

Who has married many women but was never married?

What can go through glass without breaking it?

Before the start of the car race, John and Jacob have the same amount of fuel in their car. With this fuel, John can drive for 4 hours while Jacob can drive five hours.
After a time they realize that the amount of fuel left in John's car is 1/4th of the fuel in Jacob's.

For how long they are racing?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

How can you write nineteen in a manner that if we take out one, it becomes twenty?

There is a box. The area of its top is 240 square units, the area of the front is 300 square units and the area of the end is 180 square units.

Can you calculate the dimensions of this box with the given data?

Count the number of squares in the picture below.

Two prisoners Jack and Jill are locked in a cell.
There is open window approx 40 feet above the ground of the cell.
They are never able to reach there.

Then they plan to escape by a tunnel and they start digging out.
After digging for more than 20 days, Jill comes with the different plan and they escaped.

what was the plan ?